This invention relates to a spindle apparatus for a machine tool, and more particularly to a machine tool spindle apparatus including a spindle which is rotated with a tool attached to a distal end thereof.
In a machine tool spindle apparatus of the type described, when the product of the number of blades of a tool and a rotational frequency of a spindle or an integral multiple of this product is in agreement with a natural vibration of the spindle or in the vicinity of this natural vibration, resonance (chattering vibration) occurs, so that a machined surface is often rough.
In order to prevent the generation of such resonance, there has been proposed a method in which the machining is effected with a reduced number of revolutions of the spindle so that the product of the number of the blades of the tool and the rotational frequency of the spindle or an integral multiple of this product will not brought into agreement with the natural vibration of the spindle (see, for example, JP-A-2002-039177).
However, when the machining is carried out with the reduced number of revolutions of the spindle as described above, there is encountered a problem that the time required for the machining operation increases.